ORAU TEAM 

Dose Reconstruction 

Project for NIOSH

Oak Ridge Associated Universities I Dade Moeller & Associates I MJW Corporation 

Page 1 of 10

Document Title: 

Use of Rocky Flats Neutron Dose 

Reconstruction Project Data in Dose 

Reconstructions 

Document Number: ORAUT-OTIB-0050 

Revision: 00 

Effective Date: 12/13/2005 

Type of Document: OTIB 

Supersedes: None 

Subject Expert: Matthew H. Smith 

Document Owner 

Approval: Signature on File Approval Date: 11/29/2005 

Edward F. Maher, Task 5 Manager 

Concurrence: Signature on File Concurrence Date: 12/07/2005 

Kate Kimpan, Project Director 

Approval: Signature on File Approval Date: 12/13/2005 

James W. Neton, Associate Director for Science 

 New Total Rewrite Revision Page Change 

FOR DOCUMENTS MARKED AS A TOTAL REWRITE, REVISION, OR PAGE CHANGE, REPLACE THE PRIOR 

REVISION AND DISCARD / DESTROY ALL COPIES OF THE PRIOR REVISION. 
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 2 of 10 

PUBLICATION RECORD 

EFFECTIVE 

DATE 

REVISION 

NUMBER DESCRIPTION 

12/13/2005 00 New technical information bulletin to establish guidance for the use of 

Rocky Flats Neutron Dose Reconstruction Project data in dose 

reconstructions. First approved issue. Training is required. Initiated 

by Matthew H. Smith. 
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 3 of 10 

TABLE OF CONTENTS 

SECTION TITLE PAGE

Acronyms and Abbreviations..................................................................................................................4

1.0 Purpose.......................................................................................................................................5

2.0 Application and Limitations .........................................................................................................5

3.0 Background.................................................................................................................................5

4.0 General Approach.......................................................................................................................6

 4.1 Use of Neutron Dose Reconstruction Project Data in Dose Reconstructions................ 6

 4.1.1 Minimized Dose...................................................................................................6

 4.1.2 Maximized Dose..................................................................................................6

 4.1.3 Best-Estimate Dose.............................................................................................7

 4.1.4 1970 Neutron Dose .............................................................................................7

 4.1.5 Missed Neutron Dose..........................................................................................7

 4.1.6 Neutron-to-Photon Ratio, 1970 to 1976 ..............................................................8

 4.2 Gamma Dosimetry ......................................................................................................... 8

 4.2.1 NDRP Reported Gamma Dose ...........................................................................8

 4.2.2 Reconstructed Gamma Dose ..............................................................................9

 4.2.3 Missed Gamma Dose..........................................................................................9

References ...........................................................................................................................................10

LIST OF TABLES 

TABLE TITLE PAGE

4-1 Annual N-P ratio for 1977 to 2000 ..............................................................................................8
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 4 of 10 

ACRONYMS AND ABBREVIATIONS 

DOE U.S. Department of Energy 

EEOICPA Energy Employees Occupational Illness Compensation Program Act 

GM geometric mean 

GSD geometric standard deviation 

NDRP Neutron Dose Reconstruction Project 

NIOSH National Institute for Occupational Safety and Health 

N-P neutron-to-photon 

PDF Portable Document Format 

RFP Rocky Flats Plant 

TIB technical information bulletin 

U.S.C. United States Code 

σ standard deviation 

§ Section 
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 5 of 10 

1.0 PURPOSE

 Technical information bulletins (TIBs) are general working documents that provide guidance 

 concerning the preparation of dose reconstructions at particular sites or categories of sites. 

 They will be revised in the event additional relevant information is obtained. TIBs may be used 

 to assist the National Institute for Occupational Safety and Health (NIOSH) in the completion 

 of individual dose reconstructions. 

 In this document the word “facility” is used as a general term for an area, building, or group of 

 buildings that served a specific purpose at a site. It does not necessarily connote an “atomic 

 weapons employer facility” or a “Department of Energy [DOE] facility” as defined in the Energy 

 Employees Occupational Illness Compensation Program Act of 2000 [EEOICPA; 42 U.S.C. § 

 7384l(5) and (12)]. 

 The purpose of this document is to provide guidance on the application of neutron dose from 

 the Rocky Flats Neutron Dose Reconstruction Project (NDRP) to NIOSH dose reconstructions. 

 In addition to neutron dose guidance, this TIB includes information about NDRP reconstructed 

 gamma dose and methods to determine missed gamma dose utilizing the NDRP 

 reconstructed gamma dose. 

2.0 APPLICATION AND LIMITATIONS

 Except for the application of N-P ratios as described in Section 4.1.6, the methods described 

 in this TIB apply only to workers at Rocky Flats Plant (RFP) plutonium facilities during the 

 period from 1952 to 1970. There are three important caveats or limitations: 

• The final NDRP neutron dose for 1970 may not be accurate. Recorded dosimeter data 

 was not always complete. 

• The gamma dose information for 1970 may not be present. 

• The information on gamma dose was collected only when applicable to NDRP effort. 

• Neutron dose for energy employees not included in the NDRP should continue to be 

 calculated in accordance with the Rocky Flats external dose technical basis document 

 (ORAUT 2004). 

3.0 BACKGROUND

 The NDRP data are in three main types of Portable Document Format (PDF) files. The NDRP 

 protocol document contains detailed descriptions of the content of these files (ORISE 2005). 

• Neutron Dose Summary – Yearly summary of the neutron dose components, the errors 

 associated with the values, and reconstructed gamma dose 

• Neutron Dose Detail – Details by exchange period in a given year of the neutron dose 

 components 

• Individual Timeline – Further details by exchange period in a given year about the 

 original neutron dose, calculation of NDRP dose, the building location, and penetrating 

 gamma dose 

 The total neutron dose needed for dose reconstruction consists of three quantities listed in the 

 summary and detail presentations. These quantities are: 
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 6 of 10 

• Non-affected original neutron dose – The original neutron dose equivalent that was not 

 affected by an NDRP dose based on a reread film or glass plate. A blank in this field 

 indicates either that the original neutron dose was affected or that there was no original 

 neutron dose on the dosimetry worksheet for a given monitoring period. 

• NDRP neutron dose – The neutron dose estimate from the NDRP evaluation (from reread 

 films or glass plates). A blank in this field indicates either that the original neutron dose 

 was verified to be correct or that the original film or plates were unreadable. 

• Notional neutron dose – The neutron dose equivalent estimated by the NDRP evaluation 

 for each gap. Notional dose is a weighted combination of two dose determination 

 methods. Method 1 is based on the worker’s average neutron dose per day obtained from 

 films reevaluated by the NDRP for a given calendar year and building. Method 2 is based 

 on applying an average neutron-to-gamma ratio to reported penetrating gamma doses for 

 a given building and calendar year. ORISE (2005, Section 11.3) contains a 

 comprehensive description of the notional dose calculation. A blank in this field indicates 

 that either the original dose report was correct or that the reread film or plate (dose under 

 the “NDRP Neutron Dose” heading) was adequate to replace the original film, or that there 

 was no indication of neutron exposure based on the buildings the employee was in and 

 that there was no gamma dose that could be used to estimate the exposure. 

 The Neutron Dose Summary file provides error values for the annual doses in the form of 

 standard deviations (1σ) for the NDRP and notional doses. The NDRP and notional doses 

 have normal distributions with 1-σ error values. The non-affected dose also has a normal 

 distribution, but dose reconstructors must calculate the error associated with this component in 

 accordance with External Dose Reconstruction Implementation Guideline (NIOSH 2002) and 

 Supplementary External Dose Information for Rocky Flats Plant (ORAUT 2005). 

4.0 GENERAL APPROACH

 4.1 Use Of Neutron Dose Reconstruction Project Data In Dose Reconstructions

 This section provides guidance for the use of the NDRP neutron dose components in 

 different types of reconstructions. 

 4.1.1 Minimized Dose

 In situations where only a minimum value of NDRP dose is necessary to 

 complete a NDRP reconstruction, the dose reconstructor should apply the final 

 neutron dose in the Neutron Dose Summary file as a constant. This quantity 

 consists of the non-affected original neutron dose, the NDRP neutron dose, and 

 the notional neutron dose without modification by uncertainty values. 

 4.1.2 Maximized Dose

 In situations where a maximized NDRP dose can be applied to a 

 reconstruction, the uncertainty values associated with each dose component 

 can be added to the respective doses to estimate a 95% upper confidence 

 interval dose. The summed 95% upper confidence level dose may be applied 

 as a constant. The Neutron Dose Summary file provides annual 1-σ values for 

 NDRP neutron dose and notional neutron dose and these may be multiplied by 
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 7 of 10 

 1.645 to estimate a 95% uncertainty. For non-affected original neutron dose, 

 dose reconstructors should use the 95% uncertainty factors in ORAUT (2005). 

 In addition, for data from 1951 to 1963, dose reconstructors must multiply the 

 non-affected original neutron dose by 2.50 to account for unmonitored neutron 

 dose below 800 keV. This is the most claimant favorable value from the Rocky 

 Flats external dose technical basis document (ORAUT 2004). 

4.1.3 Best-Estimate Dose

 For dose reconstructions that require a best estimate of NDRP dose, dose 

 reconstructors should combine the three components and their associated 

 uncertainties as specified in Section 2.1.1.3.4 of NIOSH (2002) using the 

 annual 1-σ values for NDRP neutron dose and notional neutron dose in the 

 Neutron Dose Summary file. For non-affected original neutron dose, dose 

 reconstructors should use the 95% uncertainties provided in ORAUT (2005) to 

 calculate a 1-σ value. In order to account for unmonitored neutron dose below 

 800 keV for data from 1951 to 1963, dose reconstructors should multiply only 

 the non-affected original neutron dose by the appropriate location/job specific 

 value from Table 6-18 of the external dose TBD depending on the specific work 

 location of the claimant, if known. If the work location is not known then the 

 maximum value applicable from Table 6-18 of the RFP TBD should be used . 

 4.1.4 1970 Neutron Dose

 The 1970 NDRP data do not conform to the standards applied to previous 

 years as explained in ORISE (2005). For reconstructions where maximized 

 dose can be used, the difference between original neutron dose and the NDRP 

 neutron dose can be added to the overall penetrating dose reported by DOE in 

 site dosimetry files, which is a combination of photon and neutron dose. When 

 a minimized or best-estimate value is needed, a neutron-to-photon (N-P) ratio 

 (see section 4.1.6 in this document) can be used to evaluate the reported 

 penetrating dose (total neutron plus photon dose in the DOE site dosimetry 

 files) and determine the neutron and gamma components. 

 4.1.5 Missed Neutron Dose

 In some instances, there is no NDRP dose or notional dose reconstructed for a 

 listed dosimeter cycle. If there is no entry for the NDRP or notional dose, it 

 should not be assumed to be a zero. However, if there is a zero in the 

 unchanged original reported neutron dose or the NDRP evaluation dose, or 

 notional dose, and the final dose is zero, then missed dose is appropriate. This 

 situation is evident upon examination of the neutron section of the Individual 

 Timeline files. When a missed dose occurs, dose reconstructors should 

 calculate the missed neutron dose using the one-half limit of detection (LOD/2) 

 method in NIOSH (2002) for that reported final zero. Estimated missed neutron 

 dose should not be applied if the original reported zero value has been changed 

 to a final positive result by the NDRP reevaluation of dosimeter results or 

 application of the notional dose. 
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 8 of 10 

 4.1.6 Neutron-to-Photon Ratio, 1970 to 1976

 The NDRP report provides N-P ratios for the period from 1952 to 1969. 

 Because the dose data from DOE contain a penetrating quantity that is a 

 combination of neutron and gamma dose through 1976, application of N-P 

 ratios to reported dose for the period from 1970 to 1976 must occur in order to 

 determine the specific neutron and gamma components of the penetrating 

 dose. Due to significant changes in operations at RFP after 1969, NDRP 

 project staff indicated that data for the period from 1977 to the present should 

 be used to determine an N-P ratio for the period from 1970 to 1976. All NIOSH 

 worker data from 1977 to the present were analyzed, and a N-P ratio was 

 determined for those claims that exhibited a positive neutron dose. The N-P 

 ratio data for this period fit a lognormal distribution with a geometric mean (GM) 

 of 0.42 and a geometric standard deviation (GSD) of 3. Dose reconstructors 

 should use those values to determine the portion of the DOE-recorded 

 penetrating dose attributable to neutron exposure for reconstructions that 

 involve employment between 1970 and 1976. Table 4-1 provides a summary of 

 the analyzed N-P ratio data. 

Table 4-1. Annual N-P ratio for 1977 to 2000. 

Year GM GSD 

1977 0.33 3.31 

1978 0.57 2.53 

1979 0.37 3.31 

1980 0.43 2.57 

1981 0.51 2.41 

1982 0.4 2.4 

1983 0.42 3.01 

Year GM GSD 

1984 0.41 3.07 

1985 0.42 3.37 

1986 0.49 2.93 

1987 0.36 3.56 

1988 0.6 2.83 

1989 0.36 3.5 

1990 0.35 3.77 

Year GM GSD 

1991 0.29 2.41 

1992 0.4 2.03 

1993 0.61 1.93 

1994 0.41 2.35 

1995 0.35 2.28 

1996 0.26 4.1 

1997 0.44 2.18 

Year GM GSD 

1998 0.39 3.03 

1999 0.45 2.79 

2000 0.6 1.8 

Overall 0.42 3 

 In order to determine the portions of penetrating dose attributable to gamma 

 and neutron exposure the following relationships can be used: 

• Gamma Dose = Penetrating Dose/1.42 

• Neutron Dose = (Penetrating Dose) – (Gamma Dose) 

 The results for gamma and neutron dose should be applied as a lognormal 

 distribution with a geometric standard deviation of 3. This approach can be 

 used for all cases whether compensable or non-compensable. 

 4.2 Gamma Dosimetry

 This section provides guidance for the use of the NDRP gamma dose components. 

4.2.1 NDRP Reported Gamma Dose

 As noted earlier, the NDRP reported gamma dose only includes those gamma 

 doses that were in some way used to estimate neutron dose and thus are 

 usually less than the DOE dosimetry reports from the site. In some cases the 

 gamma dose in the NDRP evaluation files is greater than the penetrating 

 gamma dose reported in the DOE site dosimetry files. In that event, the greater 
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 9 of 10 

 dose should be used for maximizing and best-estimate cases. The smaller 

 dose may be used for minimizing cases. 

 4.2.2 Reconstructed Gamma Dose

 For workers who had wrist dosimetry but no whole-body dosimetry, the NDRP 

 project calculated a reconstructed gamma dose based on a ratio of wrist to 

 whole-body dose. Both the Summary file and the gamma section of the 

 Individual Timeline file list this dose denoted by an asterisk (*). Because this 

 gamma dose does not appear in the original DOE data, dose reconstructors 

 should add it to the reconstruction. 

 4.2.3 Missed Gamma Dose

 The Individual Timeline files provide gamma data for each readout cycle that 

 was needed to estimate neutron dose. As discussed above, the gamma data is 

 not necessarily complete for any year (including 1970), as that was not the 

 purpose of the NDRP evaluation, and so cannot be used to directly estimate the 

 number of recorded zeros. However, the reported positive results can be 

 subtracted from the maximum number of likely zeros based on the RFP 

 external TBD; this would represent the maximum number of zeros possible. 

 The minimum number of zeros can be estimated by directly counting reported 

 zeros in the Individual Timeline file. A best estimate of zeros should apply the 

 approach discussed in OCAS-IG-001 (NIOSH 2002). This data will allow more 

 accurate estimation of the number of recorded zero doses for purposes of 

 calculating the missed gamma dose using the LOD/2 method. 
Document No. ORAUT-OTIB-0050 Revision No. 00 Effective Date: 12/13/2005 Page 10 of 10 

REFERENCES 

NIOSH (National Institute for Occupational Safety and Health), 2002, External Dose Reconstruction 

Implementation Guideline, OCAS-IG-001, Rev. 1, Office of Compensation Analysis and 

Support, Cincinnati, Ohio. 

ORAUT (Oak Ridge Associated Universities Team), 2004, Technical Basis Document for Rocky Flats 

Plan t- Occupational External Dosimetry, ORAUT-TKBS-0011-6, Rev. 00, Oak Ridge, 

Tennessee. 

ORAUT (Oak Ridge Associated Universities Team), 2005, Supplementary External Dose Information 

for Rocky Flats Plant, ORAUT-OTIB-0027, Rev. 0, Oak Ridge, Tennessee. 

ORISE (Oak Ridge Institute of Science and Education), 2005, Technical Basis Document for the 

Neutron Dose Reconstruction Project, ORISE 05-0199, Oak Ridge, Tennessee, February 7.